Google Merchant Center now uses your marketing email content “in places across Google such as Search, Shopping, and Maps.”

From the docs:

What information does Google extract?
Google crawls through the marketing content to gather relevant data, including, but not limited to:

• Links to primary social media channels
• Highlighted social media content
• Upcoming or current sales and promotions
• Brand images and videos
• Brand voice and values

Not great if you like VIP offers for subscribers.

Opt-in by default. Big G may auto-subscribe or may need to be added to your list manually.